Slow magnet



July 5, 1927.] 1,635,005

N. E. NORSTROM I snow MAGNET Filed De. 1a. 1926 operated from rent over the Wires 4 and 5. The arinature Patented July 5, 1927.

PATENT OFFICE.

NILS E. nonsrnom, or CHICAGO, umors.

SLOW MAGNET.

Application filed December 16, 1926. Serial No. 155,152.

My invention relates to slow magnets and has for its object the production of an electro-magnet which will serve as a power drive when operated by an alternating current slower than that which is in most common use.

It is generally common to operate electric lighting by alternating currents of sixty cycles per second, andelectro-magnetic instruments such as massage vibrators and hair clippers aresuccessfully operated by such a current. But in many places, alternating currents of twenty-live, thirty or forty cycles are in use, and the present electro-magnetic devices will not operate successfully at such slow rates of alternations. The object 1 here is to make an electro-magi nctic device of ordinary construction which will operate successfully at these loW alternations.

In electro-magnetic devices opera-ted by n'iake-and-break in a direct current, magnets are made slow by enclosing them in copper jackets, the copper of, the jacket serving to allcct the magnetic field so as to delay the rapidity of magnetic attraction. I aocom-' plish a similar result in magnets operated by alternating currents by substituting a hardened steel armature for the soft iron armature ordinarily used.

' 1n the accompanying drawing I have shown an ordinary magnet consisting of coils 1 and 2 connected by a keeper 3, and

a source of alternating cur- (i is ofhardened steel and is secured at 7 to an armature lever which may be a stifi spring 8 secured at 9 to a stationary ob ect 10. The spring is given an initial tension which would carrythe armature toward the poles of the magnet,,but a screw 11 near the support .10 serves to adjust the armature away from the poles of the magnet. I

Assuming an instant when the current thru the magnet makes its poles north and south as indicated by N and S, induction will magnetize the armature so that its ends are S and N as marked, and the armature is attracted. As the current reverses, the attraction of the magnet passes thru the Zero stage and the armature is retracted by the spring.

\Vhen the direction of the current is fully reversed, the armature is again attracted. It the armature is of soft iron, the previously induced magnetism disappears almost instantly, and the armature feels the attractive force as soon as the reversal of the cur rent passes the zero point.

But it the armature is of hard steel, the induced magi'ietism does not disappear instantly, but lingers so that for a time after the current passes the Zero point in reversal, N opposes N and S opposes S. The result is that an electro-magnetic device of this construction having a hardened steel armature is sluggish as compared to one of the same construction, but having an armature of soft ron.

The present device is to be distinguished from magnets having polarized arinatures pivoted between their ends and the ends opposite thepoles of the coils. Such magnets do not reverse the polarity of the ends of their armatures, and are not slow.

Applicant uses an armature in which the polarity of its ends is reversed at each alter nation of the current thru the coils which control the arn'iature, and then makes the magnet slow by making the armature so that the reversal of induction therein is delayed.

lVhat I claim is:

A magnet provided with connections to a source of alternating current, an armature composed of hardened steel, and an armature lever arranged to support the armature so that both ends thereof approach and recede simultaneously with respect to the poles of the magnet.

NILS E. NORSTROM. 

